从文本文件读取到类中的对象向量 - 在另一个 txt 文件中写入

Question

我已经更改了代码，现在程序正确读取了来自 student.txt 的文件，但仍然根据用户输入而不是 student.txt 计算
#include #include #include #include #include #include #include #include

using namespace std;

//Declaring class Student   

class Student
{
private:

  string newName;
  int newScore1;
  int newScore2;
  int newScore3;
  float newFinal;

public:
  // No argument constructors
  Student ()

 {
  newName     = " ";
  newScore1   = 0;
  newScore2   = 0;
  newScore3   = 0;
  newFinal    = 0.00;

 }
 //all arguements constructors
 Student (string name, int score1, int score2, int score3, float final)

 {
 newName     = name;
 newScore1   = score1;
 newScore2   = score2;
 newScore3   = score3;
 newFinal      = final;
 } 
 //getters
 string getName() const
 {
  return newName;
 }
 int getScore1() const
 {
 return newScore1;
 }
 int getScore2()const
 {
 return newScore2;
 }
 int getScore3()const
 {
 return newScore3;
 }

 float getFinal () const
 {
  return newFinal;
 }

 //Setters
 void setName(string name)
 {
  newName = name;
 }
 void setScore1(int score1)
 {
 newScore1=score1;
 }
 void setScore2(int score2)
 {
  newScore2=score2;
 }
 void setScore3 (int score3)
 {
 newScore3 = score3;
 }

 void setFinal (float final)
 {
    newFinal = final;
 }


};
//asks for number of students, 
// function asks for input to fill in vector
//sorts the inputs to get max 2 scores out of 3 
//puts the data in a vector of class Student
//Sends data to a text file students.txt
 void fillvector(vector <Student>& newMyClass)

{
 string name;
 float score1;
 float score2;
 float score3;
 float final;
 float tmp;
 cout << "Please enter the number of Students: " << endl;
 int classSize;
 cin >> classSize;
 for (int i = 0; i < classSize; i ++)
   {
   cout << "Enter Student's name" << endl;
   cin >> name;
   cout << "Enter Student's Score 1" << endl;
   cin >> score1;
   cout << "Enter Student's Score 2" << endl;
   cin >> score2;
   cout << "Enter Student's Score 3" << endl;
   cin >> score3;
   if(score1>score2)
     {
      float tmp = score1;
      score1 = score2;
      score2 = tmp;
     }
   if(score1>score3)
     {
     float tmp = score1;
     score1=score3;
     score3 = tmp;
     }
   if(score2>score3)
    {
     float tmp = score2;
     score2=score3;
     score3=tmp;
    }

  final = (score2+score3)/2;

  Student newStudent (name, score1, score2, score3, final);
  newMyClass.push_back(newStudent);
  cout << endl;

  ofstream myfile;
  myfile.open ("students.txt", std::ofstream::out |std::ofstream::app );
  myfile << name<< setw(5)<< score1<< setw(5)<<score2<<setw(5)  <<score3<<setw(5)<<final<<setw(5)<<endl;
  myfile.close();
  cout << "Copied to students.txt" << endl;


   }
    cout << endl;
}
//reads data from textfile students.txt
//calculated teh minimum scores and maximum scores
//sends the minimum and maximum scores to text file Results.txt
void readToVector(vector <Student>& newMyClass)

{
    string name;
float score1;
float score2;
float score3;
float finalScore;
Student newStudent (name, score1, score2, score3, finalScore);
unsigned int size = newMyClass.size();
ifstream fin("students.txt");
if (fin.is_open())
  {cout << "File open" << endl;
    while(fin >> name >> score1 >> score2 >> score3 >> finalScore)
      {
    newStudent.setName(name);
    newStudent.setScore1(score1);
    newStudent.setScore2(score2);
    newStudent.setScore3(score3);
    newStudent.setFinal(finalScore);
    newMyClass.push_back(newStudent);
    //cout << newStudent.getName() << newStudent.getFinal() << endl;

      }
     fin.close();
    cout << endl;
    Student studWMaxScore  = newMyClass[0];
    float maxscore = studWMaxScore.getFinal();

for (unsigned int i =0; i < size; i++) 
{
    if (maxscore < newMyClass[i].getFinal())
  { 
   maxscore = newMyClass[i].getFinal();
   studWMaxScore = newMyClass[i];

  }

}
cout << "Maximum Score is " << maxscore << endl;
  ofstream myfile;
   myfile.open ("Result.txt", std::ofstream::out  );
   myfile << "Maximum Score" << endl;
   myfile << maxscore << endl;
   myfile << "Name of the student with maximum score is " <<  endl;
   myfile << studWMaxScore.getName() << endl <<  endl; 
   // myfile.close();
   cout << "Copied to Results.txt" << endl; 

Student stuWMinScore = newMyClass[0];
float minscore = stuWMinScore.getFinal();
for (unsigned int i =0; i < size; i++)
{
  if (minscore > newMyClass[i].getFinal())
    {
      minscore = newMyClass[i].getFinal();
      stuWMinScore = newMyClass[i];

    }   
}
cout << "Minimum Score is " << minscore << endl; 
// ofstream myfile;
//  myfile.open ("Result.txt", std::ofstream::out );
 myfile << "Mimimum Score" << endl;
myfile << minscore << endl;
myfile << "Name of the student with minimum score is " <<  endl;
myfile << stuWMinScore.getName() << endl <<  endl;
//  myfile.close();
cout << "Copied to Results.txt" << endl;
  }
else
  cout << "file in not open" << '\n';

}


//prints out the name and scores of each student
void printVector (const vector<Student>& newMyClass)

{
unsigned int size = newMyClass.size();
for (unsigned int i =0; i < size; i++)

  {
cout << "Student name is: "<< newMyClass[i].getName() << endl;
cout << "Student Score 1 is "<< newMyClass[i].getScore1()<< endl;
cout << "Student Score 2 is "<< newMyClass[i].getScore2()<< endl;
cout << "Student Score 3 is "<< newMyClass[i].getScore3()<< endl;
cout << "Student Final Score is " << newMyClass[i].getFinal() << endl;
cout << endl; 
  }

}




int main ()

{
vector <Student> myClass;
fillvector (myClass);
readToVector(myClass);
    printVector(myClass); 
}

Answer 1

错误的核心看起来就在这里：

while(fin >> name >> score1 >> score2 >> score3 >> finalScore)
{
    newStudent.setName(name);
    newStudent.setScore1(score1);
    newStudent.setScore2(score2);
    newStudent.setScore3(score3);
    newStudent.setFinal(finalScore);
}
fin.close();
newMyClass.push_back(newStudent); 

一旦缩进被修复，很容易看到newStudent只有在文件被完全读取后才会被推入向量中。 OP 应该让最后一个学生进入向量，但其他人都没有。 由于 OP 可能希望向量中的文件中的所有学生，

while(fin >> name >> score1 >> score2 >> score3 >> finalScore)
{
    newStudent.setName(name);
    newStudent.setScore1(score1);
    newStudent.setScore2(score2);
    newStudent.setScore3(score3);
    newStudent.setFinal(finalScore);
    newMyClass.push_back(newStudent); <- moved push_back to here
}
fin.close(); <- probably not necessary

无法验证代码的其余部分，因为似乎没有 size的定义或分配——Crom 只知道那些 for 循环是否覆盖了正确的基础——或者输入的有效性，因为没有提供输入文件。 如果解析规则错误，OP 可能什么也读不出来。 调试器会比另一个 Stack Overflow 帖子更快地解决这个问题。 （OP 已经解决了这个问题）

新的东西。

我不明白为什么输入也没有解析。 首先确保文件被编码为 ASCII 文本。 我不知道你有什么工具可以在你的电脑上做到这一点。 我使用十六进制编辑器，让您以字节值而不是字符的形式查看文件，以查看字符是否与其预期的 ASCII 值不匹配。 文本编辑器可能会为您转换并隐藏差异。

例如，通常 UTF-8 编码的文件看起来与 ASCII 文件完全相同，只是在开头标记了一点二进制文件，通知阅读器程序它是一个 UTF-8 文件并且可能包含非 ASCII。

如果不是，那就是问题所在。 将该文件重新保存为 ASCII 文件。 如果是 ASCII 文件，时间最小化。 编写一个小程序，只打开文件，逐个令牌读取它，然后查看哪个令牌解析失败。 像这样的东西：

int main()
{
    ifstream fin("students.txt");
    if (fin.is_open())
    {
        int line = 0;

        while(true) // loop forever
        {
            line++;
            if (!fin >> name)
            {
                std::cout << "Could not read name on line " << line << std::endl;
                break; // exit loop
            }
            if (!fin >> score1)
            {
                std::cout << "Could not read score1 on line " << line << std::endl;
                break;
            }
            if (!fin >> score2)
            {
                std::cout << "Could not read score2 on line " << line << std::endl;
                break;
            }
            if (!fin >> score3)
            {
                std::cout << "Could not read score3 on line " << line << std::endl;
                break;
            }
            if (!fin >> finalScore)
            {
                std::cout << "Could not read finalScore on line " << line << std::endl;
                break;
            }
        }
    }
    else
    {
       std::cout << "Could not open file" << std::endl;
    }
}

一旦您知道文件在哪里失败，您就可以提出一个新问题。 这个有点过于庞大了。